Make Not expression JSON serializable

pyiceberg/expressions/__init__.py

@@ -35,6 +35,8 @@
 
 from pydantic import Field
 
+from pydantic import Field, model_validator
+
 from pyiceberg.expressions.literals import (
     AboveMax,
     BelowMin,
@@ -341,21 +343,27 @@ def __getnewargs__(self) -> Tuple[BooleanExpression, BooleanExpression]:
         return (self.left, self.right)
 
 
-class Not(BooleanExpression):
+class Not(IcebergBaseModel, BooleanExpression):
     """NOT operation expression - logical negation."""
 
     child: BooleanExpression
 
-    def __new__(cls, child: BooleanExpression) -> BooleanExpression:  # type: ignore
+    @model_validator(mode="before")
+    def _before(cls, values: Any) -> Any:
+        if isinstance(values, BooleanExpression):
+            return {"child": values}
+        return values
+
+    @model_validator(mode="after")
+    def _normalize(cls, model: Any) -> Any:
+        child = model.child
         if child is AlwaysTrue():
             return AlwaysFalse()
         elif child is AlwaysFalse():
             return AlwaysTrue()
         elif isinstance(child, Not):
             return child.child
-        obj = super().__new__(cls)
-        obj.child = child
-        return obj
+        return model
 
     def __repr__(self) -> str:
         """Return the string representation of the Not class."""

tests/expressions/test_expressions.py

@@ -738,6 +738,29 @@ def test_not() -> None:
     assert not_ == pickle.loads(pickle.dumps(not_))
 
 
+def test_not_json_serialization_and_deserialization() -> None:
+    expr = Not(AlwaysFalse())
+    json_str = expr.model_dump_json()
+    restored = Not.model_validate_json(json_str)
+    assert isinstance(restored, AlwaysTrue)
+
+    expr2 = Not(Not(AlwaysFalse()))
+    json_str2 = expr2.model_dump_json()
+    restored2 = Not.model_validate_json(json_str2)
+    assert isinstance(restored2, AlwaysFalse)
+
+    class DummyExpr(BooleanExpression):
+        def __invert__(self) -> BooleanExpression:
+            return self
+
+    dummy = DummyExpr()
+    not_dummy = Not(child=dummy)
+    json_str3 = not_dummy.model_dump_json()
+    restored3 = Not.model_validate_json(json_str3)
+    assert isinstance(restored3, Not)
+    assert isinstance(restored3.child, DummyExpr)
+
+
 def test_always_true() -> None:
     always_true = AlwaysTrue()
     assert always_true.model_dump_json() == '"true"'